Aside from humans, the only species recorded to have lifelong same-sex partnerships is male domestic sheep (BBC). Although many species display bisexual behavior, the following five species engage in same-sex female relationships.

The Laysan Albatross population on Oahu, Hawaii contain 31% female couples as pairing parents. Female albatross mate with other females for the survival of their offspring; an endeavor that takes two parents to raise one chick per season. "They rear chicks, fathered by males that are already in a committed pair but which sneak matings with one or both of the females" (BBC) And because Albatross have a tendency towards monogamy, once lesbian albatross mate, it's for life.

Sex is something animals use to their advantage, and it seems bottlenose dolphins aren't any different from humans. Both females and males display bisexual behaviour to help them create strong social bonds within their pods.

5. Spotted Hyenas

As matriarchs, female spotted hyenas dominate the male hyenas in the family structure, being larger in stature and physically more aggressive (Kay E. Holekamp Lab) which also seems to result in female spotted hyenas mounting other females as dominant sexual acts.